For weighted pull ups, how does positioning the weight below the hips (eg a dip belt) make the motion harder than when placed on the back (eg a bag)?)

Question

I have been doing pull-ups for a while and decided to recently transition into weighted pull-ups for more growth. When gathering advice, I discovered that placing a weight between the legs, with the help of a belt, allows for more growth as it makes the exercise harder when compared to wearing the weight on your chest/back via a weightvest.

I know there is a change in the center of gravity of the weights in the two scenarios, but how does the scenario where the weight is between our legs, increase the force required to pull up, or does the force required to pull up remain the same? I tried thinking if this is related to the change in torque required, considering our elbows as a pivot point, where the second scenario will have a higher torque in the direction opposite to the torque that is exerted by me. I don't really know the real answer to this problem, and it would be appreciated if there was an answer to this. Thank You.

Answer 1

Here are my thoughts: when you pull up, some lower body twists can make the pull up easier (e.g. swinging your legs gives you extra kinetic energy which you can use to help pull yourself up). The heavy weight attached near your lower body would make such twists harder. Furthermore, even if you did twist, the weight will still stay centered, so the 'cheating' effects of twisting are lessened. Holding the weight between your legs puts more stress on your core (since you'll want to try to maintain a proper form), which will contribute to making the exercise harder.